The construction of in-hospital neutron irradiator (IHNI) started in 2007. Its building construction was completed in Dec. 2008, and the installation and test of the relevant systems were completed in Mar. 2009. The first criticality was achieved on Dec. 7, 2010. The reactor reached the full power on Jan. 22, 2010. The test results show that the final excess reactivity is 4.2 mk; the maximum continuous operation time at full power is 12 h and the power wave is less then 0.3 % during full power operation; when the positive reactivity with 4.2 mk is inserted into the reactor suddenly, the power will be increased to 85.7 kW at the time of 229 s, and then, it will turn to the normal value due to the negative temperature effect.The release result of reactivity shows the inherent safety of reactor.